Chlorites: occurrence, genesis and crystal chemistry – introduction

Extract

The crystal chemistry and mechanisms of chlorite formation (more particularly the ferrous varieties) are currently attracting growing interest in various fields of application. In oil prospection, this interest is linked to the origin and formation of diagenetic chlorite rims that preserve the quality of sandy reservoirs down to unusual depths of burial. In the nuclear industry, the use of iron containers for the storage of radioactive waste is likely to produce ferrous chlorites by interaction with the clayey barrier within which the waste is stored. The ditrioctahedral and tri-trioctahedral chlorites are also some of the best clay mineral markers of hydrothermal activity leading to the formation of uranium deposits underlying the Proterozoic unconformity that make up the largest current economic reserves.

The high chemical and structural variability of chlorite is an obstacle in understanding its mechanism of formation, transformation and alteration. This also applies to the determination of the thermodynamic parameters that are required for digital models based on thermo-kinetic laws.